JP2003214713A - Refrigeration cycle device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem of a refrigeration cycle device using carbon dioxide as a refrigerant, wherein the arrangement of a receiver on a low pressure side increases cost and volume owing to a pressure-resistant design for safety securement and the like. <P>SOLUTION: The arrangement of a first bypass circuit bypassing an inlet and an outlet of a radiator via a first flow regulating valve, and a second bypass circuit bypassing the radiator outlet and a decompressor inlet via a second flow regulating valve can control an internal heat exchange quantity. Without a low pressure receiver, as an intake refrigerant state in a compressor is controlled to an appropriate state, a coefficient of performance (COP) can be increased. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a refrigeration cycle apparatus using carbon dioxide (hereinafter referred to as CO2 refrigerant) as a working medium.

[0002]

2. Description of the Related Art A working fluid in a recent refrigeration cycle apparatus is a conventional CFC refrigerant or HCFC refrigerant which is considered to have a harmful effect on the ozone layer, and an HFC refrigerant or HC having an ozone depletion coefficient of 0 as an alternative refrigerant. It is being transferred to a refrigerant.

However, HFC refrigerants have the drawback of having a large global warming potential as a property of substances, while HC
Refrigerants have a low global warming potential, but have the drawback of being highly flammable. Further, although the ammonia refrigerants that have been used conventionally have a global warming potential of 0, they have the drawback of being weakly flammable and toxic.

Therefore, CO2, which has almost no global warming potential as a substance, is nonflammable, nontoxic, and low cost
Refrigerants are receiving attention. However, the CO2 refrigerant is
The critical temperature is as low as 31.1 ° C, and the CO2 refrigerant does not condense on the high pressure side of the normal refrigeration cycle apparatus. For this reason,
As shown in FIG. 14 shown in Japanese Patent Application No. 3-515570, by having a heat exchange means for exchanging heat between the outlet line of the high-pressure side cooler and the suction line of the compressor, the outlet of the cooler is A means for supercooling and lowering the high pressure is used, and a low pressure receiver is provided as a capacity management means by adjusting the amount of refrigerant.

[0005]

However, providing a receiver at a low pressure has a drawback that the cost and volume increase, and in the actual operating range, the HCFC refrigerant and the HFC refrigerant used in the conventional refrigeration cycle apparatus are used.
Considering that the pressure of the CO2 refrigerant becomes very high with respect to the refrigerant, the pressure resistance design for ensuring safety becomes more severe.

To solve the above-mentioned problems, the invention utilizes a characteristic of a CO2 refrigeration system in a refrigeration cycle apparatus using a CO2 refrigerant, reduces the size of a low-voltage receiver or does not use it, while ensuring reliability and efficiency. An object of the present invention is to provide a refrigeration cycle device that enables various operations.

[0007]

In order to solve the above-mentioned problems, the present invention uses carbon dioxide as a refrigerant, at least a compressor, a radiator, an internal heat exchanger for exchanging heat between a radiator outlet and a suction line, and a pressure reducer. A bypass circuit that has an evaporator and bypasses an inlet and an outlet of a radiator via an on-off valve, an evaporator temperature detecting unit that detects a temperature of the evaporator, and a suction temperature of the compressor. The suction temperature detecting means is provided.

Further, the present invention has at least a compressor, a radiator, an internal heat exchanger, a decompressor, and an evaporator using carbon dioxide as a refrigerant, and the inlet and outlet of the radiator are the first flow rate adjusting valve. A first bypass circuit that bypasses the internal heat exchanger via a second flow rate adjusting valve between the radiator outlet and the pressure reducer inlet is provided.

Further, according to the present invention, an oil separator for separating the refrigerating machine oil discharged from the compressor from the refrigerant and returning it to the compressor by using carbon dioxide as a refrigerant, and an oil returning flow rate of the oil separated from the oil separator. An oil return circuit for returning to the suction of the compressor via a regulating valve is provided.

Further, the present invention uses carbon dioxide as a refrigerant, at least a compressor, a refrigerant water heat exchanger, a first pressure reducer, a first heat exchanger, an internal heat exchanger, a second pressure reducer, and a second pressure reducer. 2
And a bypass circuit for bypassing an inlet and an outlet of the first heat exchanger via a flow rate adjusting valve, and a first heat exchange for detecting a refrigerant temperature of the first heat exchanger. A refrigerating cycle characterized by having a cooling medium temperature detecting means, and a hot water cycle having a pump for circulating hot water heated by the refrigerant water heat exchanger, a hot water heater core, and a radiator.

Further, according to the present invention, the refrigerant water heat exchanger inlet and outlet are bypassed via a third flow rate adjusting valve.
The bypass circuit is provided.

The present invention is also provided with speed detecting means for detecting the traveling speed of the vehicle.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) FIG. 1 is a configuration diagram showing a refrigeration cycle apparatus according to Embodiment 1 of the present invention.
This refrigeration cycle apparatus uses CO2 refrigerant as a working fluid,
The compressor 1, the radiator 2, the internal heat exchanger 3, the pressure reducer 4, and the evaporator 5 are the basic constituent elements. The outlet line of the radiator 2 and the suction line of the compressor 1, which is the outlet of the evaporator 4, are
The internal heat exchanger 3 is configured to perform heat exchange. Further, a bypass circuit 7 is provided for bypassing the inlet and outlet of the radiator via a solenoid valve 6 (open / close valve).

The operation of the solenoid valve 6 will be described with reference to the flowchart of FIG.

When the rotation is started, the value Teva detected by the evaporator temperature detecting means 9 is compared with the value Ts detected by the compressor suction temperature detecting means 8 in step 51. Then, when the value of Ts is equal to or less than Teva, the routine proceeds to step 52, where the solenoid valve 6 is controlled to "open" to increase the heat radiation amount in the internal heat exchanger 3. As a result, the compressor suction refrigerant temperature rises, so that the degree of superheat rises and it is possible to prevent the liquid refrigerant from being sucked into the compressor. As a result, the amount of heat exchange in the internal heat exchanger can be increased, so that it is possible to bring the refrigerant sucked into the compressor into a heated state, and ensure the reliability of the compressor without providing a low-pressure receiver. can do.
When the value of Ts is larger than Teva, the routine proceeds to step 53, where the opening degree of the solenoid valve 6 is controlled to be small and the heat radiation amount of the radiator 2 is controlled to be large.

(Second Embodiment) FIG. 3 is a block diagram showing a refrigeration cycle apparatus according to a second embodiment of the present invention.
Hereinafter, the points different from the first embodiment will be described. This refrigeration cycle apparatus includes a first flow rate adjusting valve 10, a first bypass circuit 11, a second flow rate adjusting valve 12, and a second bypass circuit 13. Here, the first flow rate adjusting valve 1
The operation of 0 and the second flow rate adjusting valve 12 will be described with reference to the flowchart of FIG.

When the operation is started, at step 54, T
eva and Ts are compared. When Ts is equal to or lower than Teva, the process proceeds to step 55, and the first flow rate adjusting valve 10
The opening degree of the second flow rate control valve 12 is controlled to be fully closed by controlling the opening degree of the second flow rate adjusting valve 12 to be fully opened, thereby increasing the heat radiation amount in the internal heat exchanger. Thus, the flow rate of the refrigerant flowing through the internal heat exchanger is controlled to be increased. As a result, the compressor suction refrigerant temperature rises, so that the degree of superheat rises and it is possible to prevent the liquid refrigerant from being sucked into the compressor. When Ts is larger than Teva, the routine proceeds to step 56, where the first flow rate adjusting valve 1
The opening degree of 0 is controlled to be small, and the opening degree of the second flow rate adjusting valve 12 is controlled to be large, so that Ts is adjusted to a target value (for example, Teva). In this way, by setting the suction state of the compressor to an appropriate state, it is possible to improve the heat exchange performance in the evaporator and to secure the reliability of the compressor without providing a low pressure receiver. it can.

(Embodiment 3) FIG. 5 is a block diagram showing a refrigeration cycle apparatus according to Embodiment 3 of the present invention.
Hereinafter, points different from the second embodiment will be described. This refrigeration cycle device is provided with an oil separator 14, an oil return flow rate adjusting valve 15, and an oil return circuit 16.

At the time of starting the compressor, there is a problem that the liquid refrigerant lying in the evaporator or the like is sucked into the compressor to lower the reliability.

The operation of the first flow rate adjusting valve 10, the second flow rate adjusting valve 12 and the oil return flow rate adjusting valve 15 under such conditions will be described below with reference to the flow chart of FIG.

When the operation is started, at step 57, T
eva and Ts are compared. When Ts is equal to or lower than Teva, the process proceeds to step 58, and the first flow rate adjusting valve 10
Is controlled to be fully open, the second flow rate control valve 12 is fully closed, and the oil return control valve 15 is controlled to be large in opening, and the high temperature oil heated in the discharge stroke of the compressor is controlled. The control is performed so that the suction temperature of the compressor rises due to the return of a large amount. This makes it possible to more reliably prevent the liquid refrigerant from being sucked into the compressor. On the other hand, when Ts is larger than Teva at step 57, the routine proceeds to step 59, where the opening degree of the second flow rate adjusting valve 12 is increased so that the opening degree of the first flow rate adjusting valve 10 is decreased. As described above, by controlling the opening degree of the oil return adjusting valve 15 to be small, Ts is adjusted to a target value (for example, Teva). In this way, by setting the suction state of the compressor to an appropriate state, it is possible to improve the heat exchange performance in the evaporator and to secure the reliability of the compressor without providing a low pressure receiver. it can.

(Fourth Embodiment) FIG. 7 is a block diagram showing a refrigeration cycle apparatus according to a fourth embodiment of the present invention.
Hereinafter, points different from the third embodiment will be described. This refrigeration cycle device includes a refrigerant water heat exchanger 20, a first pressure reducer 21, a first heat exchanger 26, a second pressure reducer 22, and a second heat exchanger 27, and the first heat exchanger A refrigeration cycle characterized by comprising first heat exchanger temperature detection means 28 for detecting the refrigerant temperature of the heat exchanger 26, and a pump 29 for circulating the hot water heated by the refrigerant water heat exchanger 20, A hot water heater core 25, a radiator 23, and a hot water cycle having an engine 24 are provided.

In the heating operation, when the outdoor temperature is low, such as in winter, or when the amount of heat of evaporation is large, the evaporation temperature may be 0 ° C. or lower, and frost may form on the evaporator, resulting in a decrease in the COP of the refrigeration system. There is a problem. Hereinafter, the first pressure reducer 2 during the heating operation under such conditions
The operations of the first and second pressure reducers 22, the first flow rate adjusting valve 10, and the second flow rate adjusting valve 12 will be described with reference to the flowchart of FIG.

When the operation of the refrigeration cycle device is started,
In step 60, the value T1 detected by the first heat exchanger temperature detecting means 28 is compared with the target temperature set value Tx (for example, 0 ° C.). When T1 is equal to or lower than Tx, the process proceeds to step 61, in which the first pressure reducer 21 is controlled to be fully opened and the second pressure reducer 22 is controlled to maintain a high-low pressure balance. The heat exchanger 26 is operated as a radiator, and the opening of the first flow rate adjusting valve 10 is fully closed and the opening of the second flow rate adjusting valve 12 is controlled to be large. The heat radiation amount of 26 is controlled to be large. As a result, the temperature of the refrigerant in the first heat exchanger 26 can be raised, frost formation can be quickly melted, and performance deterioration of the refrigeration cycle apparatus can be prevented. After that, the routine proceeds to Step 63, and at Step 63, by performing the same operation as at Step 54 described above, the suction state of the compressor is set to an appropriate state, so that the heat exchange performance in the evaporator is enhanced. In addition, the reliability of the compressor can be ensured without providing a low pressure receiver. On the other hand, in step 60, when T1 is larger than Tx, the process proceeds to step 62, the first pressure reducer 21 is controlled so as to maintain a high-low pressure balance, and the second pressure reducer 22 is fully opened. The opening degree of the first flow rate adjusting valve 10 is controlled to be fully closed, and the opening degree of the second flow rate adjusting valve 12 is controlled to be fully closed, and the process returns to step 60.

(Fifth Embodiment) FIG. 9 is a block diagram showing a refrigeration cycle apparatus according to a fifth embodiment of the present invention.
Hereinafter, points different from the fourth embodiment will be described. This refrigeration cycle device is provided with a third bypass circuit 31 that bypasses the water-refrigerant heat exchanger 20 via a third flow rate adjusting valve. Here, the operation of the third flow rate adjusting valve 30 will be described with reference to the flowchart of FIG.

When the operation is started, in step 66,
The value T1 detected by the first heat exchanger temperature detecting means 28 is compared with the target temperature set value Tx (for example, 0 ° C.). If T1 is less than or equal to Tx, step 6
7, the opening degree of the first pressure reducer 21 is reduced and the opening degree of the third flow rate adjusting valve 30 is controlled to be increased, whereby the flow rate of the refrigerant flowing through the water-refrigerant heat exchanger is decreased. Then, the amount of heat released from the first heat exchanger 26 is controlled to be increased. As a result, the frost can be melted more quickly, and the performance of the refrigeration cycle device can be prevented from being degraded. Then, move to step 69 and step 6
In No. 9, by performing the same operation as in Step 54 described above, the suction state of the compressor is set to an appropriate state, so that the heat exchange performance of the second heat exchanger 27 acting as an evaporator is enhanced. In addition, the reliability of the compressor can be ensured without providing a low pressure receiver. On the other hand, when T1 is larger than Tx in step 66, the process proceeds to step 68, the third flow rate adjusting valve is controlled to be fully closed, and the process returns to step 60.

(Sixth Embodiment) FIG. 11 is a configuration diagram showing a refrigeration cycle apparatus according to a sixth embodiment of the present invention. Hereinafter, points different from the fifth embodiment will be described.
This refrigeration cycle device is provided with a vehicle traveling speed detecting means 32 for detecting the traveling speed of the vehicle.

As the vehicle speed increases, the outdoor heat exchanger (first
Since the cooling fan air volume of the heat exchanger 26) of
There is a problem that once defrosting occurs in the heat exchanger, the defrosting operation time becomes long. The operation under such a condition will be described below with reference to FIGS. 12 and 13.

When the operation of the refrigeration cycle device is started,
In step 72, the value T1 detected by the first heat exchanger temperature detecting means 28 is compared with the target temperature set value Tx (for example, 0 ° C.). When T1 is equal to or less than Tx, the process proceeds to step 73, and the vehicle traveling speed detection means 3
The vehicle speed is detected by 2, and the process proceeds to step 74. At step 74, as shown in FIG. 13, the first flow rate adjusting valve 10 controls so that the opening degree becomes smaller as the vehicle speed becomes higher, and the third flow rate adjusting valve 30 becomes larger as the vehicle speed becomes larger. Control to be. As a result, the amount of heat released from the first heat exchanger is controlled to increase as the vehicle speed increases. As a result, the frost can be effectively and quickly melted, and the performance of the refrigeration cycle device can be prevented from being degraded. Then move to step 76,
Ts and Teva are compared, and if Ts is larger than Teva, the process returns to step 72. When Ts is equal to or lower than Teva, the same operation as in step 55 described above is performed to set the suction state of the first compressor to an appropriate state, thereby enhancing the heat exchange performance in the evaporator. In addition, the reliability of the compressor can be ensured. on the other hand,
When T1 is larger than Tx in step 72, the process proceeds to step 75, the third flow rate adjusting valve 30 is controlled to be fully closed, and the process returns to step 72.

[0031]

As is apparent from the above description,
The present invention, in a refrigeration apparatus using carbon dioxide as a refrigerant, by providing a bypass circuit that bypasses the inlet and outlet of the radiator via a solenoid valve (opening / closing valve), the amount of heat exchange in the internal heat exchanger. Can be increased,
It is possible to put the refrigerant sucked into the compressor into an overheated state,
The reliability of the compressor can be ensured without providing a low voltage receiver.

Further, a first bypass circuit for bypassing the inlet and the outlet of the radiator via the first flow rate adjusting valve,
By providing a second bypass circuit that bypasses the radiator outlet and the pressure reducer inlet via the second flow rate adjusting valve, the amount of internal heat exchange can be controlled, so that the state of the refrigerant sucked into the compressor is appropriate. Coefficient of performance (C
OP) can be increased.

Further, by providing an oil separator for separating the refrigerating machine oil discharged from the compressor from the refrigerant, and an oil return circuit for returning the separated oil to the compressor via the oil return flow rate adjusting valve, Since the suction state of the compressor can be brought into the overheated state more quickly and reliably even at the time of startup, the reliability of the compressor can be ensured without providing the low pressure receiver.

In the vehicle air conditioner using carbon dioxide as a refrigerant, the refrigerant water heat exchanger, the first pressure reducer and the second pressure reducer, and the inlet and outlet of the first heat exchanger are flown. By providing a refrigerating cycle characterized by including a bypass circuit bypassing via a regulating valve and a refrigerant temperature detecting means for detecting the refrigerant temperature of the first heat exchanger, even when the outside air temperature is low. Since the generation of frost on the first heat exchanger can be suppressed, highly efficient operation can be performed.

Further, when frost is formed on the first heat exchanger by providing a third bypass circuit for bypassing the inlet and the outlet of the refrigerant water heat exchanger via a third flow rate adjusting valve. Moreover, since the heat exchange amount of the first heat exchanger can be controlled more appropriately, a quick defrosting operation can be performed.

Further, by providing the speed detecting means for detecting the traveling speed of the vehicle, the first flow rate adjusting valve and the third flow rate adjusting valve are appropriately controlled in accordance with the traveling speed, so that the first speed can be increased more quickly. The defrosting operation of the heat exchanger can be performed.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a refrigeration cycle apparatus that is an embodiment of the present invention.

FIG. 2 is a control flowchart of the refrigeration cycle apparatus according to the embodiment of the present invention.

FIG. 3 is a configuration diagram of a refrigeration cycle apparatus according to another embodiment of the present invention.

FIG. 4 is a control flowchart of a refrigeration cycle apparatus according to another embodiment of the present invention.

FIG. 5 is a configuration diagram of a refrigeration cycle apparatus according to another embodiment of the present invention.

FIG. 6 is a control flowchart of the refrigeration cycle apparatus according to another embodiment of the present invention.

FIG. 7 is a configuration diagram of a refrigeration cycle device according to another embodiment of the present invention.

FIG. 8 is a control flowchart of the refrigeration cycle apparatus according to another embodiment of the present invention.

FIG. 9 is a configuration diagram of a refrigeration cycle apparatus according to another embodiment of the present invention.

FIG. 10 is a control flowchart of a refrigeration cycle device according to another embodiment of the present invention.

FIG. 11 is a configuration diagram of a refrigeration cycle apparatus according to another embodiment of the present invention.

FIG. 12 is a control flowchart of the refrigeration cycle apparatus according to another embodiment of the present invention.

FIG. 13 is a diagram showing a relationship between a flow control valve opening and a vehicle speed of a refrigeration cycle device according to another embodiment of the present invention.

FIG. 14 is a configuration diagram of another conventional refrigeration cycle apparatus.

[Explanation of symbols]

1 compressor 2 radiator 3 Internal heat exchanger 4 pressure reducer 5 evaporator 6 Solenoid valve 7 Bypass circuit 8 Compressor suction temperature detection means 9 Evaporator temperature detection means 10 First flow control valve 11 First bypass circuit 12 Second flow control valve 13 Second bypass circuit 14 Oil separator 15 Oil return flow rate adjustment valve 16 Oil return circuit 20 Water refrigerant heat exchanger 21 First decompressor 22 Second decompressor 23 radiator 24 engine 25 heater core 26 First heat exchanger 27 Second heat exchanger 28 First heat exchanger temperature detecting means 29 pumps 30 Third flow control valve 31 Third Bypass Circuit 32 Vehicle traveling speed detection means

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) F25B 1/00 395 F25B 1/00 395Z B60H 1/32 624 B60H 1/32 624F 624G 624J F24H 1/00 611 F24H 1/00 611Z F25B 39/04 F25B 39/04 L (72) Inventor Fumitoshi Nishiwaki 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Noriho Okaza 1006 Kadoma, Kadoma City, Osaka Prefecture Address: Matsushita Electric Industrial Co., Ltd.

Claims (6)

[Claims] 1. An internal heat exchanger for exchanging heat between a compressor, a radiator, a radiator outlet and a suction line using carbon dioxide as a refrigerant, a pressure reducer, and an evaporator, and having an inlet and an outlet of the radiator. A refrigeration cycle apparatus comprising: a bypass circuit for bypassing through an on-off valve; an evaporator temperature detecting means for detecting the temperature of the evaporator; and a suction temperature detecting means for detecting a suction temperature of the compressor. . 2. At least a compressor, a radiator, an internal heat exchanger, a decompressor, and an evaporator using carbon dioxide as a refrigerant,
A first bypass circuit that bypasses the inlet and outlet of the radiator via the first flow rate adjusting valve, and a radiator outlet and the pressure reducer inlet that bypass the internal heat exchanger via the second flow rate adjusting valve. A refrigeration cycle device comprising a second bypass circuit for 3. An oil separator, which separates refrigerating machine oil discharged from the compressor with the refrigerant and returns to the compressor, using carbon dioxide as a refrigerant, and an oil separated from the oil separator through an oil return flow rate adjusting valve. The refrigeration cycle apparatus according to claim 1 or 2, further comprising an oil return circuit for returning to the compressor suction. 4. Carbon dioxide as a refrigerant, at least a compressor, a refrigerant water heat exchanger, a first pressure reducer, a first heat exchanger, an internal heat exchanger, a second pressure reducer, a second heat exchange. Circuit having a heat exchanger and bypassing an inlet and an outlet of the first heat exchanger via a flow rate adjusting valve, and a first heat exchanger refrigerant temperature for detecting a refrigerant temperature of the first heat exchanger A refrigeration cycle apparatus comprising: a refrigeration cycle provided with a detection means; and a hot water cycle having a pump for circulating hot water heated by the refrigerant water heat exchanger, a hot water heater core, and a radiator. . 5. The refrigerant water heat exchanger has a third inlet and outlet.
5. The refrigeration cycle apparatus according to claim 4, further comprising a third bypass circuit that bypasses the flow rate adjusting valve. 6. The refrigeration cycle apparatus according to claim 4 or 5, further comprising speed detection means for detecting a traveling speed of the vehicle.